Catheters for the introduction or removal of fluids may be located in various venous locations and cavities throughout the body of a patient for the introduction of fluids to the body or removal of fluids from the body. Such catheterization may be performed by using a single catheter assembly having multiple lumens. A typical example of a multiple lumen catheter assembly is a dual lumen catheter assembly in which one lumen introduces fluids and one lumen removes fluids. Catheterization may also be performed by using separate, single lumen catheters inserted into an area to be catheterized. Examples of such multiple catheter assemblies are TESIO® catheters sold by Medical Components, Inc. of Harleysville, Pa.
Generally, to insert any catheter in a blood vessel, the vessel is identified by aspiration with a long hollow needle in accordance with the Seldinger technique. When blood enters a syringe attached to the needle, indicating that the vessel has been found, a thin guidewire is then introduced, typically through a syringe needle or other introducer device, into the interior of the vessel. The introducer device is then removed, leaving the end portion of the guidewire that has been inserted into the vessel within the vessel and the opposing end of the guidewire projecting beyond the surface of the skin of the patient.
At this point, several options are available to a physician for catheter placement. The simplest is to pass a catheter assembly into the vessel directly over the guidewire. The guidewire is then removed, leaving the catheter assembly in position within the vessel. However, this technique is only possible in cases where the catheter assembly is of a relatively small diameter, made of a stiff material and not significantly larger than the guidewire. For example, this technique may be used to insert small diameter dual lumen catheters into a patient. If the catheter assembly to be inserted is significantly larger than the guidewire, a dilator device is first passed over the guidewire to enlarge the hole. The dilator is then removed, and the catheter assembly is then passed over the guidewire into the vessel. The guidewire is then removed.
In the case of an individual, singe-lumen catheter typically used in multiple catheter assemblies (e.g., a TESIO® catheter assembly), a physician may use an introducer sheath. If a TESIO® catheter assembly is used for hemodialysis, for example, each catheter is inserted in two separate veins, such as femoral veins. Alternatively, each catheter may be inserted in two different locations of the same vein, such as the internal jugular vein. The introducer sheath is simply a large, stiff thin-walled tube which serves as a temporary conduit for the permanent catheter which is being placed. The introducer sheath is positioned by placing a dilator device inside of the introducer sheath and passing both the dilator and the introducer sheath together into the vessel over a guidewire. The guidewire, left in the vessel after its insertion as described above, and the dilator are then removed, leaving the thin-walled introducer sheath in place. The catheter is placed into the vessel through the introducer sheath. After the catheter is inserted into the vessel, the sheath is then torn from around the catheter and removed. Preferably, the catheter is inserted into the patient's vessel a predetermined distance, depending on the size of the patient and the physician's preference.
Typically, one catheter in the assembly, the venous catheter, is inserted farther into the patient than the other catheter in the assembly, the arterial catheter, to provide better blood circulation through the catheter assembly. Each of the catheters in the assembly is typically subcutaneously secured within the patient's body by a cuff located in a subcutaneous tunnel, or by otherwise externally affixing the catheter to the body.
The TESIO® catheter assembly may also be inserted in accordance with the technique described in U.S. Pat. No. 5,624,413 through a single insertion point using a sheath into the vessel. The TESIO® catheter assembly, once inserted in the vessel, is then tunnelled separately through the patient in two subcutaneous tunnels leading to outside the body of the patient, where the external, proximal portions of the catheter preferably are secured. After tunneling, clamps and luer locks are secured to the proximal end of each catheter in the assembly for connection to an external device, such as a hemodialysis machine.
One problem experienced by physicians while inserting the TESIO® catheter assembly occurs after the catheter assembly is inserted into the vessel, is that occasionally, while subcutaneously tunneling the catheter assembly through the body of the patient, the distal end of one or both catheters in the assembly may be pulled away from the predetermined location in which the physician initially inserted the catheter. Such a situation could reduce the effectiveness of the hemodialysis process. It would be beneficial to provide a mechanism by which the individual catheters in the catheter assembly are secured relative to each other, and in which the physician can determine whether the placement of the catheters in the vessel has changed after the catheter is inserted into the vessel.